linux-kernel - [RFC v1 23/26] x86/tdx: Make pages shared in ioremap()

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Message-Id: <33ced467eae950bc3df9e1f01284036fd560d33c.1612563142.git.sathyanarayanan.kuppuswamy@linux.intel.com>
Date:   Fri,  5 Feb 2021 15:38:40 -0800
From:   Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...el.com>
Cc:     Andi Kleen <ak@...ux.intel.com>,
        Kirill Shutemov <kirill.shutemov@...ux.intel.com>,
        Kuppuswamy Sathyanarayanan <knsathya@...nel.org>,
        Dan Williams <dan.j.williams@...el.com>,
        Raj Ashok <ashok.raj@...el.com>,
        Sean Christopherson <seanjc@...gle.com>,
        linux-kernel@...r.kernel.org,
        Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>
Subject: [RFC v1 23/26] x86/tdx: Make pages shared in ioremap()

From: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>

All ioremap()ed paged that are not backed by normal memory (NONE or
RESERVED) have to be mapped as shared.

Reuse the infrastructure we have for AMD SEV.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
Reviewed-by: Andi Kleen <ak@...ux.intel.com>
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
---
 arch/x86/include/asm/pgtable.h | 3 +++
 arch/x86/mm/ioremap.c          | 8 +++++---
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index a02c67291cfc..a82bab48379e 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -21,6 +21,9 @@
 #define pgprot_encrypted(prot)	__pgprot(__sme_set(pgprot_val(prot)))
 #define pgprot_decrypted(prot)	__pgprot(__sme_clr(pgprot_val(prot)))
 
+/* Make the page accesable by VMM */
+#define pgprot_tdx_shared(prot) __pgprot(pgprot_val(prot) | tdx_shared_mask())
+
 #ifndef __ASSEMBLY__
 #include <asm/x86_init.h>
 #include <asm/fpu/xstate.h>
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index 9e5ccc56f8e0..a0ba760866d4 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -87,12 +87,12 @@ static unsigned int __ioremap_check_ram(struct resource *res)
 }
 
 /*
- * In a SEV guest, NONE and RESERVED should not be mapped encrypted because
- * there the whole memory is already encrypted.
+ * In a SEV or TDX guest, NONE and RESERVED should not be mapped encrypted (or
+ * private in TDX case) because there the whole memory is already encrypted.
  */
 static unsigned int __ioremap_check_encrypted(struct resource *res)
 {
-	if (!sev_active())
+	if (!sev_active() && !is_tdx_guest())
 		return 0;
 
 	switch (res->desc) {
@@ -244,6 +244,8 @@ __ioremap_caller(resource_size_t phys_addr, unsigned long size,
 	prot = PAGE_KERNEL_IO;
 	if ((io_desc.flags & IORES_MAP_ENCRYPTED) || encrypted)
 		prot = pgprot_encrypted(prot);
+	else if (is_tdx_guest())
+		prot = pgprot_tdx_shared(prot);
 
 	switch (pcm) {
 	case _PAGE_CACHE_MODE_UC:
-- 
2.25.1